JP2010118337A - Additive for electrolyte - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an additive for an electrolyte capable of increasing output of a secondary battery and restraining deterioration on charge and discharge cycle characteristics. <P>SOLUTION: In the additive for an electrolyte wherein at least one nitrogen atom in nitrogen-containing onium salt is bonded with an organic group (a) having polymerized unsaturated bonding, and the nitrogen atom or the other nitrogen atom includes the nitrogen-containing onium salt (A) having a structure combined with (poly)oxyalkylene chain (b), it is preferable that the nitrogen-containing onium salt (A) becomes imidazolium salt and/or quaternary ammonium salt. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an additive for electrolytic solutions. More specifically, the present invention relates to an electrolytic solution additive for forming a negative electrode protective film and an electrolytic solution containing the same.

  In recent years, there is an increasing demand for secondary batteries that can be repeatedly charged and discharged as power supply devices for electronic products such as mobile phones and personal computers. Among them, lithium secondary batteries are actively developed because they can be increased in voltage, reduced in size, and reduced in weight. Conventionally, for the purpose of improving the battery characteristics of a lithium secondary battery, attempts have been made to mix various additives into the electrolytic solution. For example, in Patent Documents 1 and 2, vinylene carbonate (hereinafter abbreviated as VC) is used in order to prevent the carbonic acid ester used as the electrolyte from being decomposed at the negative electrode and deteriorating the charge / discharge cycle characteristics. ) And vinyl ethylene carbonate (hereinafter abbreviated as VEC) are added to the electrolytic solution, and VC, VEC, etc. are electropolymerized on the negative electrode to form a negative electrode protective film. ing.

  However, since the negative electrode protective film produced from the carbonate having a double bond contains a large amount of lithium carbonate, the lithium ion conductivity is not sufficient and the output of the lithium secondary battery is lowered. In addition, since the adhesion of the negative electrode protective film is insufficient, there is a problem that deterioration of charge / discharge cycle characteristics cannot be sufficiently suppressed.

JP 2003-151621 A JP 2003-031259 A

  An object of this invention is to provide the additive for electrolyte solutions which increases the output of a secondary battery and suppresses that a charge / discharge cycle characteristic falls.

  The inventors of the present invention have reached the present invention as a result of studies to achieve the above object. That is, the present invention relates to an organic group (a) in which at least one nitrogen atom in a nitrogen-containing onium salt has a polymerizable unsaturated bond via an alkylene chain [hereinafter, simply referred to as an organic group (a) or (a) Sometimes written. And a nitrogen-containing onium salt (A) having a structure in which the nitrogen atom or another nitrogen atom is bonded to the polyoxyalkylene chain (b) [hereinafter, a nitrogen-containing onium salt (A) or (A ). ] And the electrolyte solution containing the said electrolyte solution additive.

  When the additive for electrolytic solution of the present invention is added to the electrolytic solution, there is an effect that the output of the secondary battery is increased and the charge / discharge cycle characteristics are suppressed from being deteriorated.

  Hereinafter, the present invention will be described in more detail. The nitrogen-containing onium salt (A) in the present invention is an onium salt having one or more (preferably one or two) nitrogen atoms in the cation portion of the onium salt. In the nitrogen-containing onium salt (A), at least one nitrogen atom is bonded to an organic group (a) having a polymerizable unsaturated bond. Since the onium salt has the polymerizable unsaturated bond, it becomes easy to form a polymer as a protective film on the negative electrode surface of the secondary battery, and a protective film with good adhesion is formed. The output is increased, and the effect of suppressing the deterioration of the charge / discharge cycle characteristics is exhibited. The nitrogen atom of the nitrogen-containing onium salt (A) is bonded to the (poly) oxyalkylene chain (b). By having a (poly) oxyalkylene chain, the adhesion of the secondary battery as a negative electrode protective film is further improved, so that the output of the secondary battery is increased and the charge / discharge cycle characteristics are suppressed from being deteriorated. There is an effect.

Examples of the nitrogen-containing onium salt (A) include amine salts, amidinium salts, and ammonium salts. Examples of the amine salt include salts obtained by adding protons to primary to tertiary amines. Examples of amidinium salts include imidazolinium salts, imidazolium salts, pyrimidinium salts, and tetrahydropyrimidinium salts. Examples of ammonium salts include ammonium ion (NH ₄ ) salts and quaternary ammonium salts. Among the nitrogen-containing onium salts (A), from the viewpoint of charge / discharge cycle characteristics, amidinium salts and ammonium salts are preferable, and imidazolium salts and quaternary ammonium salts are more preferable.

  Examples of the imidazolium salt include a salt represented by the general formula (1).

In the formula, R ¹ is a hydrogen atom, a methyl group or an ethyl group; R ² is an alkylene group having 2 to 4 carbon atoms; R ³ is an alkyl group having 1 to ³ carbon atoms; Q is an organic group having a polymerizable unsaturated bond. (a); m is the number of 1 to 10; X ^- represents an anion.

R ¹ is preferably a hydrogen atom and a methyl group from the viewpoint of charge / discharge cycle characteristics, and more preferably a hydrogen atom. Examples of R ² include an ethylene group, a propylene group, and a butylene group. From the viewpoint of charge / discharge cycle characteristics, preferred are an ethylene group and a propylene group, and more preferred is an ethylene group. Examples of R ³ include a methyl group, an ethyl group, and a propyl group, and a methyl group is preferable from the viewpoint of charge / discharge cycle characteristics. m is preferably 2 to 7 from the viewpoint of charge / discharge cycle characteristics, and more preferably 2 to 5. (R ² O) m is the above-mentioned (poly) oxyalkylene chain (b). When m is 1, it is an oxyalkylene group, and when m is 2 to 10, it is a polyoxyalkylene chain. In the present invention, an oxyalkylene group and a polyoxyalkylene chain are collectively referred to as a (poly) oxyalkylene chain.

  The organic group (a) having a polymerizable unsaturated bond in the present invention is an organic group having a polymerizable ethylenically unsaturated bond. For example, the group represented by the general formula (3), the general formula (4) ), A (meth) acryloyloxyalkyl group, a (meth) acryloylalkyl group, and the like. Among these, the group represented by the general formula (3), the group represented by the general formula (4), and the (meth) acryloyloxyalkyl group are preferable from the viewpoint of charge / discharge cycle characteristics.

In the formula, R ⁶ is an alkylene group having 1 to 3 carbon atoms, Q ¹ , Q ² and Q ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, a halogen atom, or a fluoroalkyl. A group selected from the group consisting of a group, a cyano group, a carboxyl group, an alkoxy group and an alkoxycarbonyl group.
Examples of the alkylene group having 1 to 3 carbon atoms include a methylene group, an ethylene group, a 1,2-propylene group, and a 1,3-propylene group. Among these, a methylene group and an ethylene group are preferable from the viewpoint of compatibility with the electrolytic solution.
Examples of the alkyl group having 1 to 4 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, and t-butyl group.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
Examples of the fluoroalkyl group include those in which 1 to 5 hydrogen atoms on a methyl group or an ethyl group are substituted with fluorine atoms. For example, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a fluoroethyl group, Examples thereof include a difluoroethyl group, a trifluoroethyl group, a tetrafluoroethyl group, and a pentafluoroethyl group.
As an alkoxy group, a C1-C3 alkoxy group is mentioned, For example, a methoxy group, an ethoxy group, n-propoxy group, and an isopropoxy group are mentioned.
Examples of the alkoxycarbonyl group include those having 1 to 3 carbon atoms of the alkoxy group, such as a methoxycarbonyl group, an ethoxycarbonyl group, an n-propoxycarbonyl group, and an isopropoxycarbonyl group.

Preferred combinations of Q ¹ , Q ² and Q ³ include the following (1) to (6).
(1) Q ¹ = hydrogen atom, Q ² = hydrogen atom, Q ³ = phenyl group (2) Q ¹ = hydrogen atom, Q ² = hydrogen atom, Q ³ = alkoxycarbonyl group (3) Q ¹ = phenyl group, Q ² = hydrogen atom, Q ³ = phenyl group (4) Q ¹ = phenyl group, Q ² = hydrogen atom, Q ³ = alkoxycarbonyl group (5) Q ¹ = alkoxycarbonyl group, Q ² = hydrogen atom, Q ³ = Phenyl group (6) Q ¹ = Alkoxycarbonyl group, Q ² = Hydrogen atom, Q ³ = Alkoxycarbonyl group Of these combinations, the combination of (2) is more preferred.

In the formula, R ⁷ is an alkylene group having 1 to 3 carbon atoms, Q ⁴ is a hydrogen atom or a halogen atom, and Q ⁵ , Q ⁶ and Q ⁷ are each independently a hydrogen atom and a carbon number of 1 to 4 alkyl groups, phenyl groups, halogen atoms, fluoroalkyl groups, cyano groups, carboxyl groups, alkoxy groups, and alkoxycarbonyl groups. Specific examples of these groups include the same groups as those exemplified for R ⁶ , Q ¹ , Q ² and Q ³ . Of Q ⁴ , a hydrogen atom, a fluorine atom and a chlorine atom are preferred from the viewpoint of charge / discharge cycle characteristics and the stability of the organic group (a) having a polymerizable unsaturated bond, and more preferred are hydrogen atoms. is there. Of Q ^5, a hydrogen atom is preferable from the viewpoint of charge / discharge cycle characteristics. Of Q ⁶ and Q ^7, a hydrogen atom and a methyl group are preferable from the viewpoint of charge / discharge cycle characteristics, and a hydrogen atom is more preferable.

Preferred combinations of Q ⁴ , Q ⁵ , Q ⁶ and Q ⁷ include the following (1) to (12).
(1) Q ⁴ = hydrogen atom, Q ⁵ = hydrogen atom, Q ⁶ = hydrogen atom, Q ⁷ = hydrogen atom (2) Q ⁴ = fluorine atom, Q ⁵ = hydrogen atom, Q ⁶ = hydrogen atom, Q ⁷ = Hydrogen atom (3) Q ⁴ = chlorine atom, Q ⁵ = hydrogen atom, Q ⁶ = hydrogen atom, Q ⁷ = hydrogen atom (4) Q ⁴ = hydrogen atom, Q ⁵ = hydrogen atom, Q ⁶ = methyl group, Q ⁷ = hydrogen atom (5) Q ⁴ = fluorine atom, Q ⁵ = hydrogen atom, Q ⁶ = methyl group, Q ⁷ = hydrogen atom (6) Q ⁴ = chlorine atom, Q ⁵ = hydrogen atom, Q ⁶ = methyl group Q ⁷ = hydrogen atom (7) Q ⁴ = hydrogen atom, Q ⁵ = hydrogen atom, Q ⁶ = hydrogen atom, Q ⁷ = methyl group (8) Q ⁴ = fluorine atom, Q ⁵ = hydrogen atom, Q ⁶ = hydrogen atom, ^{Q 7} = methyl group (9) ^{Q 4} = a chlorine atom, ^{Q 5} = hydrogen atom, ^{Q 6} = hydrogen atom, ^{Q 7} = methyl 10) ^{Q 4} = a hydrogen atom, ^{Q 5} = hydrogen atom, ^{Q 6} = methyl group, ^{Q 7} = methyl group (11) ^{Q 4} = fluorine atom, ^{Q 5} = hydrogen atom, ^{Q 6} = methyl group, ^{Q 7} = methyl Group (12) Q ⁴ = chlorine atom, Q ⁵ = hydrogen atom, Q ⁶ = methyl group, Q ⁷ = methyl group Of these combinations, the combination of (1) is more preferred.

  Examples of the (meth) acryloyloxyalkyl group in the organic group (a) having a polymerizable unsaturated bond in the present invention include an acryloyloxyethyl group and a methacryloyloxymethyl group.

  Examples of the (meth) acryloylalkyl group in the organic group (a) having a polymerizable unsaturated bond in the present invention include an acryloylethyl group and a methacryloylethyl group.

X ⁻ in the general formula (1) includes Cl ⁻ , Br ⁻ , I ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , SbF ₆ ⁻ , AsF ₆ ⁻ , ClO ₄ ⁻ , N (CF ₃ SO ₂ ) ₂ ⁻ , _{N (C 2 F 5 SO 2} ) 2 -, C (CF 3 SO 2) 3 - , and the like. Among these, preferred from the viewpoints of cell output and charge-discharge cycle _{^{characteristics, PF 6 -, BF 4 -}} , SbF 6 -, AsF 6 - and ClO ₄ ^- it is, more preferred PF ₆ ^- is.

Specific examples of the imidazolium salt include N- (2-butenoic acid methyl) -N ′-(3,6-dioxaheptyl) imidazolium hexafluorophosphate [in the general formula (1), R ¹ represents a hydrogen atom. R ² is an ethylene group, R ³ is a methyl group, Q is a group represented by the general formula (3), R ⁶ is a methylene group, Q ¹ and Q ² are hydrogen atoms, and Q ³ is a methoxycarbonyl group , and the a m is 2, X- is PF ₆ ^- compounds in which], N-(2-butenoate) -N '- (3,6-dioxaheptyl) -2-ethyl imidazolium hexafluoro Fluorophosphate, N- (methyl 2-butenoate) -N ′-(2-oxabutyl) imidazolium tetrafluoroborate, N- (3-acryloyloxypropyl) -N ′-(3,6-dioxaheptyl ) Imidazouriu Muhexafluoroantimonate, N- (3-acryloyloxypropyl) -N '-(3,6,9-trioxadecyl) imidazolium hexafluorophosphate, N- (methyl 2-butenoate) -N'- (2-methoxyethyl) -2-methylimidazolium tetrafluoroborate, N- (3-acryloyloxypropyl) -N ′-(3,6-dioxaheptyl) -2-methylimidazolium hexafluorophosphate N- (3-acryloyloxypropyl) -N ′-(3,6,9-trioxadecyl) imidazolium tetrafluoroborate, N- (methyl 2-butenoate) -N ′-(2-methoxyethyl) ) Imidazolium hexafluorophosphate, 2-ethyl-1- (3,6-dioxaheptyl) imidazolium hexafluoro Phosphate, N- (3-acryloyloxypropyl) -N ′-(3,6,9-trioxadecyl) -2-ethylimidazolium hexafluoroborate, N- (4-vinylbenzyl) -N ′-( 3,6-dioxaheptyl) -2-ethylimidazolium hexafluorophosphate, N- (4-vinylbenzyl) -N ′-(2-oxabutyl) imidazolium tetrafluoroborate, N- (4-vinylbenzyl) ) -N '-(3,6-dioxaheptyl) imidazolium hexafluoroantimonate, N- (4-vinylbenzyl) -N'-(3,6,9-trioxadecyl) imidazolium hexafluorophosphate N- (4-vinylbenzyl) -N ′-(2-methoxyethyl) -2-methylimidazolium tetrafluoroborate, N— (4-vinylbenzyl) -N ′-(2-methoxyethyl) imidazolium hexafluorophosphate, 2-ethyl-1- (3,6-dioxaheptyl) imidazolium hexafluorophosphate and N- (4- Vinylbenzyl) -N ′-(3,6,9-trioxadecyl) -2-ethylimidazolium hexafluoroborate and the like.

As a quaternary ammonium salt mentioned as a preferable thing among nitrogen-containing onium salt (A) in this invention, the salt represented by General formula (2) is mentioned.
In the formula, R ⁴ is an alkylene group having 2 to ⁴ carbon atoms, R ⁵ is an alkyl group having 1 to 3 carbon atoms, Q is an organic group (a) having a polymerizable unsaturated bond, n is a number of 1 to 5, a represents an integer of 1 to 3, and Y ⁻ represents an anion.

R ⁴ in the general formula (2) is preferably an ethylene group from the viewpoint of battery output. R ⁵ is preferably a methyl group from the viewpoint of battery output and charge / discharge cycle characteristics. n is preferably 1 to 4 from the viewpoint of battery output and charge / discharge cycle characteristics, and more preferably 1 to 3.

Examples of the organic group (a) having a polymerizable unsaturated bond represented by Q in the general formula (2) include a group represented by the general formula (3), a group represented by the general formula (4), (meta ) An acryloyloxyalkyl group and a (meth) acryloylalkyl group. Examples of Y ⁻ include the same as X ⁻ in the general formula (1).

Specific examples of the quaternary ammonium salt include methyl 2-butenoate-tri (3,6-dioxaheptyl) ammonium hexafluorophosphate [in the general formula (2), R ⁴ represents an ethylene group, R ⁵ Is a methyl group, Q is an organic group in which R ⁶ is a methylene group, Q ¹ and Q ² are hydrogen atoms, Q ³ is a methoxycarbonyl group in the general formula (3), n is 2, and a is 1 and Y ⁻ is PF ₆ ^— ], methyl 2-butenoate-tri (2-oxabutyl) ammonium hexafluorophosphate, di (methyl 2-butenoate) -di (3,6,9 -Trioxadecyl) ammonium hexafluorophosphate, (3,6,9,12,15-pentaoxahexadecyl) -tri (methyl 2-butenoate) ammonium hexafluorophosphate Fert, 3-acryloyloxypropyl-tri (3,6-dioxaheptyl) ammonium hexafluorophosphate, methyl 2-butenoate-tri (3,6-dioxaheptyl) ammonium tetrafluoroborate, 3-acryloyloxypropyl -Tri (3,6-dioxaheptyl) ammonium hexafluoroantimonate, methyl di (2-butenoate) -di (3,6,9-trioxadecyl) ammonium tetrafluoroborate, 4-vinylbenzyl-tri ( 2-oxabutyl) ammonium hexafluorophosphate, di (4-vinylbenzyl) -di (3,6,9-trioxadecyl) ammonium hexafluorophosphate, (3,6,9,12,15-pentaoxahexa) Decyl) -tri (4-vinyl benze ) Ammonium hexafluorophosphate, 4-vinylbenzyl-tri (3,6-dioxaheptyl) ammonium hexafluorophosphate, 4-vinylbenzyl-tri (3,6-dioxaheptyl) ammonium tetrafluoroborate, 4- Examples thereof include vinylbenzyl-tri (3,6-dioxaheptyl) ammonium hexafluoroantimonate and di (4-vinylbenzyl) -di (3,6,9-trioxadecyl) ammonium tetrafluoroborate.

  The method for producing the imidazolium salt and quaternary ammonium salt in the present invention is not particularly limited, and can be produced by a usual method. For example, after reacting an imidazole derivative or amine having a polyoxyalkylene chain with an alkyl halide having an organic group (a) having a polymerizable unsaturated bond in an organic solvent in the absence of a catalyst or in the presence of a catalyst, The method of anion exchange reaction is mentioned as needed. Examples of organic solvents include nitrile organic solvents (acetonitrile, propiononitrile, benzonitrile, etc.), ketone organic solvents (acetone, methyl ethyl ketone, etc.), amide organic solvents (formamide, acetamide, dimethylformamide, dimethylacetamide, etc.) , Ether organic solvents (such as dimethyl ether, tetrahydrofuran and dioxane), ester organic solvents (such as ethyl acetate and diethyl maleate), sulfur-containing organic solvents (such as dimethyl sulfoxide and sulfolane), halogenated hydrocarbons (such as chloroform and dichloromethane) , Hydrocarbons (hexane, heptane, toluene, xylene, etc.) and mixtures of two or more of these solvents. Catalysts include alkali metal hydroxides (for example, lithium hydroxide, sodium hydroxide and potassium hydroxide), alkali metal carbonates (such as sodium bicarbonate, potassium bicarbonate, sodium carbonate and potassium carbonate) and alkali metal hydrides. (Such as sodium hydride and potassium hydride). The reaction temperature is usually 10 to 150 ° C., and the reaction time is usually 0.5 to 24 hours. After completion of the reaction, if necessary, the catalyst can be neutralized and treated with an adsorbent to remove and purify the catalyst.

  Examples of the halogenated alkyl having an organic group (a) having a polymerizable unsaturated bond include 4-bromo-2-butenoic acid methyl ester, 4-chloro-2-butenoic acid methyl ester, and 1-bromo-4. -Cyano-2-butene, 1-chloro-4-cyano-2-butene, acrylic acid chloromethyl ester, acrylic acid bromomethyl ester, acrylic acid-2-chloroethyl ester, acrylic acid-2-bromoethyl ester, methacrylic acid Acid chloromethyl ester, methacrylic acid bromomethyl ester, methacrylic acid-2-chloroethyl ester, methacrylic acid-2-bromoethyl ester, 4-chloromethylstyrene, 4- (2-chloroethyl) styrene and 1- (3-chloro Propyl) styrene and the like.

  The electrolyte salt dissociation promoter (B) in the present invention comprises a sulfoxide compound and / or an ether compound, and examples of the sulfoxide compound include compounds represented by the general formula (5).

In the formula, R ⁸ and R ⁹ are each independently an alkyl group having 1 to 5 carbon atoms. Examples of the alkyl group having 1 to 5 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group and t-butyl group, n-pentyl group, isopentyl group, and 2,2. -A dimethylpropyl group etc. are mentioned. Among these, a methyl group is preferable from the viewpoint of battery output.

  Specific examples of the sulfoxide compound include dimethyl sulfoxide, ethyl methyl sulfoxide, methyl n-propyl sulfoxide, butyl methyl sulfoxide, methyl pentyl sulfoxide, diethyl sulfoxide, ethyl isopropyl sulfoxide, n-butyl ethyl sulfoxide, ethyl n-pentyl sulfoxide, diisopropyl sulfoxide. N-butyl n-propyl sulfoxide, isopentyl n-propyl sulfoxide, di-n-butyl sulfoxide, butyl 2,2-dimethylpropyl sulfoxide, diisopentyl sulfoxide and the like.

  As a manufacturing method of a sulfoxide compound, the method of oxidizing and manufacturing the alkyl sulfide which has a C1-C5 alkyl with an oxidizing agent is mentioned. Examples of the oxidizing agent include hydrogen peroxide and perhalogenates (such as sodium perchlorate, sodium perbromate, and sodium periodate). The reaction temperature is usually 0 to 100 ° C., and the reaction time is usually 1 to 10 hours. After completion of the reaction, the oxidizing agent can be decomposed with a reducing agent (sodium thiosulfate, sodium hydrogensulfite, etc.) and then treated with an adsorbent for removal and purification.

As an ether compound in this invention, the compound represented by General formula (6) is mentioned.
R ¹⁰ —O— (CH ₂ CH ₂ O) _n —R ¹¹ (6)
^{Wherein, R 10} and ^{R 11} are each independently an alkyl group of 1 to 5 carbon atoms; n is a number from 1 to 10. Examples of the alkyl group having 1 to 5 carbon atoms include those similar to R ⁸ and R ⁹ in the general formula (5). Of R ¹⁰ and R ^11, a methyl group is preferable from the viewpoint of battery output. n is preferably 1 to 2 from the viewpoint of the electrolyte viscosity.

  Specific examples of the ether compound include dimethoxyethane, diethoxyethane, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, pentaethylene glycol dimethyl ether, penta Ethylene glycol diethyl ether, hexaethylene glycol ethyl methyl ether, hexaethylene glycol n-butylisopentyl ether, heptaethylene glycol isobutyl n-propyl ether, heptaethylene glycol ethyl 2,2-dimethylpropyl ether, octaethylene glycol ethyl n-propyl ether, Kuta ethylene glycol diisobutyl ether, nonaethylene glycol dimethyl ether, nonaethylene glycol t- butyl isopropyl ether, decaethylene glycol diisopropyl ether and decamethylene glycol 2,2-dimethylpropyl isopentyl ether, and the like.

As a manufacturing method of an ether compound, the method of manufacturing through the following processes is mentioned.
(1): A monohydric alcohol having 1 to 5 carbon atoms is charged into a pressurized reaction vessel, ethylene oxide is blown in the presence of no catalyst or a catalyst, and ethylene oxide is added in one step or multiple steps under normal pressure or pressure. Perform the reaction.
(2): The hydroxyl group of the ethylene oxide adduct of a monohydric alcohol having 1 to 5 carbon atoms obtained in (1) is etherified with an etherifying agent.
As a catalyst for the addition reaction of a monohydric alcohol having 1 to 5 carbon atoms and ethylene oxide, an alkali catalyst [for example, alkali metal (lithium, sodium, potassium, cesium, etc.)] hydroxide, acid [perhalogen acid (perchlorine Acid, perbromic acid and periodic acid), sulfuric acid, phosphoric acid and nitric acid (preferably perchloric acid)] and salts thereof [preferably divalent or trivalent metals (Mg, Ca, Sr, Ba) , Zn, Co, Ni, Cu and Al). The reaction temperature is usually 50 to 150 ° C., and the reaction time is usually 2 to 20 hours. After completion of the addition reaction of ethylene oxide, the catalyst can be neutralized if necessary and treated with an adsorbent to remove and purify the catalyst.
Examples of the catalyst for the etherification reaction of an ethylene oxide adduct of a monohydric alcohol having 1 to 5 carbon atoms include hydroxides of alkali catalysts [eg, alkali metals (lithium, sodium, potassium, cesium, etc.)]. Examples of the etherifying agent include alkyl chloride or alkyl bromide having 1 to 5 carbon atoms, such as methyl chloride, methyl bromide, ethyl chloride, ethyl bromide, n-propyl chloride, n-propyl bromide, and chloride. Isopropyl, isopropyl bromide, n-butyl chloride, n-butyl bromide, isobutyl chloride, isobutyl bromide, t-butyl chloride, t-butyl bromide, n-pentyl chloride, n-pentyl bromide, isopentyl chloride, odor Isopentyl chloride, 2,2-dimethylpropyl chloride, 2,2-dimethylpropyl bromide and the like. The reaction temperature is usually 50 to 100 ° C., and the reaction time is usually 6 to 24 hours. The equivalent ratio of the etherifying agent to the ethylene oxide adduct of a monohydric alcohol having 1 to 5 carbon atoms is preferably 1 to 2. In the etherification reaction, a solvent such as toluene or benzene can be used as necessary. After completion of the reaction, the unreacted etherifying agent and solvent are distilled off under reduced pressure, the catalyst is neutralized, and the catalyst can be removed and purified by treatment with an adsorbent.

  Of the sulfoxide compounds and ether compounds, ether compounds are preferable from the viewpoint of battery capacity, and dimethoxyethane, diethoxyethane, diethylene glycol dimethyl ether, and diethylene glycol diethyl ether are more preferable from the viewpoints of volatility and electrolyte viscosity.

The number of donors of the sulfoxide compound and the polyether compound in the present invention represents the affinity between the sulfoxide compound or the polyether compound and the electrolyte, and the stabilization of coordination to SbCl _{5 in} 1,2-dichloroethane. It is a number obtained by measuring enthalpy (kcal / mol). As the number of donors of typical compounds, for example, those described in “V. Gutman, Hitoshi Ohtsuki, Isao Okada,“ Donor and Acceptor ”Society Publishing Center, published in 1983” can be used. The larger the number of donors, the higher the dissociation ability of the electrolyte. From the viewpoint of battery output, the number of donors of the sulfoxide compound and the polyether compound is preferably 16 to 40 and more preferably 20 to 30 for both the sulfoxide compound and the polyether compound. In order to increase the donor number of the sulfoxide compound in the present invention, the number of carbon atoms of the alkyl group having 1 to 5 carbon atoms of R ⁸ and R ⁹ in the general formula (5) may be reduced. In order to increase the number of donors of the ether compound in the present invention, the number of carbon atoms of the alkyl group having 1 to 5 carbon atoms of R ¹⁰ and R ¹¹ in the general formula (6) may be decreased, and the number of n may be increased. That's fine. In order to reduce the number of donors of the ether compound, the number of carbon atoms in the alkyl group having 1 to 5 carbon atoms of R ¹⁰ and R ¹¹ in the general formula (6) may be increased, and the number of n may be decreased. If the number of donors is 16 or more, the affinity with lithium ions is above a certain level, and the battery output does not decrease.

  Examples of the carbonate compound (C) having a polymerizable unsaturated bond include a chain carbonate compound (C1) having 4 to 7 carbon atoms and a cyclic carbonate compound (C2) having 3 to 9 carbon atoms. Among these, (C2) is preferable from the viewpoint of charge / discharge cycle characteristics. Examples of (C1) include methyl vinyl carbonate, ethyl vinyl carbonate, n-propyl vinyl carbonate, isopropyl vinyl carbonate, divinyl carbonate, allyl methyl carbonate, allyl ethyl carbonate, allyl n-propyl carbonate, allyl isopropyl carbonate, and diallyl carbonate. It is done. These can be obtained commercially.

  As a C3-C9 cyclic carbonate compound (C2), the compound represented by the compound represented by General formula (7) and General formula (8) is mentioned.

In the formula, R ¹² and R ¹³ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. Among these, a hydrogen atom is preferable from the viewpoint of charge / discharge cycle characteristics.

  Specific examples of the compound represented by the general formula (7) include vinylene carbonate, methyl vinylene carbonate, ethyl vinylene carbonate, n-propyl vinylene carbonate, isopropyl vinylene carbonate, dimethyl vinylene carbonate, diethyl vinylene carbonate, and di-n-propyl vinylene. Examples include carbonate, diisopropyl vinylene carbonate, ethyl methyl vinylene carbonate, ethyl n-propyl vinylene carbonate, and ethyl isopropyl vinylene carbonate. These can be obtained commercially.

In the formula, R ¹⁴ and R ¹⁵ are each independently a hydrogen atom or an alkenyl group having 2 to 3 carbon atoms, and R ¹⁴ and R ¹⁵ are not both hydrogen atoms. Examples of the alkenyl group having 2 to 3 carbon atoms include a vinyl group and an allyl group. Among these, a hydrogen atom and a vinyl group are preferable from the viewpoint of charge / discharge cycle characteristics.

  Specific examples of the compound represented by the general formula (8) include vinyl ethylene carbonate, allyl ethylene carbonate, divinyl ethylene carbonate, and diallyl ethylene carbonate. These can be obtained commercially.

  As the compound (D) having a vinyl ether group or a propenyl ether group, a linear alkyl compound having 4 to 10 carbon atoms (D1) having a vinyl ether group or a propenyl ether group at both ends, and a vinyl ether group or a propenyl ether group at both ends. And an oligoether compound (D2) having two or more vinyl ether groups or propenyl ether groups (D3). Among these, (D3) is preferable from the viewpoint of charge / discharge cycle characteristics.

  As a C4-C10 linear alkyl compound (D1) which has a vinyl ether group or a propenyl ether group in both ends, the compound represented by General formula (9) is mentioned.

R ¹⁶ —CH═CH—O— (CH ₂ ) _p —O—CH═CH—R ¹⁷ (9)
In the formula, R ¹⁶ and R ¹⁷ are each independently a hydrogen atom or a methyl group, and p is a number of 4 to 10. Among these, from the viewpoint of charge / discharge cycle characteristics, preferred are compounds in which R ¹⁶ and R ¹⁷ are hydrogen atoms and p is 6-8.

  Specific examples of the compound represented by the general formula (9) include 1,4-butanediol divinyl ether, 1,5-pentanediol divinyl ether, 1,6-hexanediol divinyl ether, and 1,7-heptanediol divinyl ether. Vinyl ether, 1,8-octanediol divinyl ether, 1,9-nonanediol divinyl ether, 1,10-decanediol divinyl ether, 1,4-butanediol propenyl vinyl ether, 1,5-pentanediol propenyl vinyl ether, 1,6 -Hexanediol propenyl vinyl ether, 1,7-heptanediol propenyl vinyl ether, 1,8-octanediol propenyl vinyl ether, 1,9-nonanediol propenyl vinyl ether, 1,10-decanediol propenyl Nyl ether, 1,4-butanediol dipropenyl ether, 1,5-pentadiol dipropenyl ether, 1,6-hexanediol dipropenyl ether, 1,7-heptanediol dipropenyl ether, 1,8-octanediol dipropenyl Examples include ether, 1,9-nonanediol dipropenyl ether and 1,10-decanediol dipropenyl ether. These can be obtained commercially.

  Examples of the oligoether compound (D2) having a vinyl ether group or a propenyl ether group at both ends include a compound represented by the general formula (10).

R ¹⁸ —CH═CH—O— (C ₂ H ₄ O) _q —O—CH═CH—R ¹⁹ (10)
In the formula, R ¹⁸ and R ¹⁹ are each independently a hydrogen atom or a methyl group, and q is a number of 1 to 5. Among these, preferred are compounds in which R ¹⁸ and R ¹⁹ are hydrogen atoms and q is 2 to 3 from the viewpoint of charge / discharge cycle characteristics.

  Specific examples of the compound represented by the general formula (10) include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, pentaethylene glycol divinyl ether, ethylene glycol propenyl vinyl ether, diethylene glycol propenyl. Vinyl ether, triethylene glycol propenyl vinyl ether, tetraethylene glycol propenyl vinyl ether, pentaethylene glycol propenyl vinyl ether, ethylene glycol dipropenyl ether, diethylene glycol dipropenyl ether, triethylene glycol dipropenyl ether, tetraethylene glycol dipropenyl ether and pentaethylene Etc. glycol dipropionate propenyl ether and the like. These can be obtained commercially.

  Specific examples of (D3) include cyclohexylpropenyl ether, 1,2-bis (propenoxymethyl) cyclohexane, 1,3-bis (propenoxymethyl) cyclohexane, 1,4-bis (propenoxymethyl) Cyclohexane, 1,3,5-tris (propenoxymethyl) cyclohexane, 1,2-bis (vinyloxymethyl) cyclohexane, 1,3-bis (vinyloxymethyl) cyclohexane, 1,4-bis (vinyloxymethyl) ) Cyclohexane and 1,3,5-tris (vinyloxymethyl) cyclohexane. These can be obtained commercially.

The nitrogen-containing onium salt (A), electrolyte dissociation accelerator (B), carbonate compound (C), and vinyl ether group or propenyl ether group based on the total weight of the electrolyte additive in the electrolyte additive of the present invention The preferred contents (% by weight) of the compound (D) are as follows.
(A) is preferably 0.1 to 100% by weight, more preferably 0.8 to 8.7% by weight from the viewpoint of charge / discharge cycle characteristics and battery capacity. (B) is preferably 0 to 97% by weight, more preferably 17.9 to 82.3% by weight from the viewpoint of battery output. (C) is preferably 0 to 90% by weight, and more preferably 15.9 to 71.4% by weight from the viewpoints of battery capacity, battery output and charge / discharge cycle characteristics. (D) is preferably 0 to 50% by weight from the viewpoint of battery capacity, battery output and charge / discharge cycle characteristics, and more preferably 0.4 to 4.3 parts by weight.

  The additive for electrolytic solution of the present invention is useful for forming a negative electrode protective film of a secondary battery. The additive for electrolytic solution of the present invention forms an electric double layer on the negative electrode in the secondary battery during initial charging, and forms a protective film by being subjected to reduction polymerization. By forming a protective film on the negative electrode, the nonaqueous solvent is prevented from being decomposed at the negative electrode, the output of the secondary battery is increased, and the charge / discharge cycle characteristics are prevented from being deteriorated.

  The electrolytic solution of the present invention contains a nonaqueous solvent, an electrolyte, and the additive for electrolytic solution.

  As the non-aqueous solvent, those used in ordinary electrolytic solutions can be used, for example, cyclic or chain carbonate ester, chain carboxylate ester, cyclic or chain ether, phosphate ester, lactone compound, nitrile compound. Amide compounds, etc., and mixtures thereof can be used. Examples of the cyclic carbonate include propylene carbonate, ethylene carbonate and butylene carbonate. Examples of the chain carbonate include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, and di-n-propyl carbonate. Examples of chain carboxylic acid esters include methyl acetate, ethyl acetate, propyl acetate, and methyl propionate. Examples of the cyclic ether include tetrahydrofuran, tetrahydropyran, 1,3-dioxolane, 1,4-dioxane and the like. Examples of the chain ether include dimethoxymethane and 1,2-dimethoxyethane. Examples of phosphate esters include trimethyl phosphate, triethyl phosphate, ethyl dimethyl phosphate, diethyl methyl phosphate, tripropyl phosphate, tributyl phosphate, tri (trifluoromethyl) phosphate, tri (trichloromethyl) phosphate, Tri (trifluoroethyl) phosphate, tri (triperfluoroethyl) phosphate, 2-ethoxy-1,3,2-dioxaphospholan-2-one, 2-trifluoroethoxy-1,3,2- Examples include dioxaphospholan-2-one and 2-methoxyethoxy-1,3,2-dioxaphosphoran-2-one. Examples of the lactone compound include γ-butyrolactone and γ-valerolactone. A nitrile compound includes acetonitrile. Examples of the amide compound include dimethylformamide. Of the nonaqueous solvents, cyclic carbonates, chain carbonates and phosphates are preferable from the viewpoint of battery output and charge / discharge recycling characteristics, and cyclic carbonates are more preferable.

  The content of the non-aqueous solvent is preferably 20 to 99% by weight and more preferably 58 to 95% by weight based on the weight of the electrolytic solution from the viewpoint of battery output and charge / discharge cycle characteristics.

As the electrolyte contained in the electrolytic solution of the present invention, those used in ordinary electrolytic solutions can be used. For example, lithium salts of inorganic acids such as LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ and LiClO ₄ , Examples thereof include lithium salts of organic acids such as LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO ₂ ) ₂ , and LiC (CF ₃ SO ₂ ) ₃ . Among these, LiPF ₆ is preferable from the viewpoint of battery output and charge / discharge cycle characteristics.

  The concentration of the electrolyte in the electrolytic solution is preferably 0.01 to 3 mol / L from the viewpoint of battery output and charge / discharge cycle characteristics based on the capacity of the electrolytic solution, and more preferably 0.05 to 1. 5 mol / L.

  The addition amount of the additive for electrolytic solution of the present invention is preferably 0.1 to 30% by weight, and more preferably 0.1 to 10% by weight based on the weight of the electrolytic solution. When the addition amount is less than 0.1% by weight, a negative electrode protective film cannot be formed. When the addition amount exceeds 30% by weight, the additive remaining in the electrolyte after charging is oxidatively decomposed at the positive electrode and battery characteristics are obtained. Is unfavorable because of lowering.

  You may add another additive to the electrolyte solution of this invention as needed. Examples of other additives include an overcharge inhibitor, a dehydrating agent, and a capacity stabilizer.

  Examples of the overcharge inhibitor include biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, aromatic compounds such as cyclohexylbenzene, t-butylbenzene, and t-amylbenzene. The usage-amount of an overcharge inhibitor is 0-5 weight% normally based on the total weight of electrolyte solution, Preferably it is 1-3 weight%.

  Examples of the dehydrating agent include zeolite, silica gel and calcium oxide. The usage-amount of a dehydrating agent is 0-5 weight% normally based on the total weight of electrolyte solution, Preferably it is 1-3 weight%.

  Examples of the capacity stabilizer include fluoroethylene carbonate, succinic anhydride, 1-methyl-2-piperidone, heptane, and fluorobenzene. The amount of the capacity stabilizer used is usually 0 to 5% by weight, preferably 1 to 3% by weight, based on the total weight of the electrolytic solution.

  The method for preparing the electrolytic solution of the present invention is not particularly limited, and can be prepared by dissolving the electrolyte, the additive for electrolytic solution of the present invention, and other additives in a non-aqueous solvent. Moreover, it is preferable to dehydrate each raw material in advance when preparing the electrolytic solution so that the amount of water in the electrolytic solution is 50 ppm or less.

  Hereinafter, although an example and a manufacture example explain the present invention further, the present invention is not limited to these. In the following, “%” means “% by weight” and “parts” means “parts by weight”.

<Production Example 1>
Production of positive electrode;
After thoroughly mixing 9.0 parts of LiCoO ₂ powder, 0.5 part of Ketjen Black [manufactured by Aldrich] and 0.5 part of polyvinylidene fluoride [manufactured by Aldrich] in a mortar, 1-methyl-2-pyrrolidone [ 7.0 parts by Tokyo Chemical Industry Co., Ltd.] was added, and further mixed well in a mortar to obtain a slurry. The obtained slurry was applied to one side of an aluminum electrolytic foil having a thickness of 20 μm using a wire bar in the atmosphere, dried at 100 ° C. for 15 minutes, and further under reduced pressure (10 mmHg) at 80 ° C. for 5 minutes. It dried and punched out to 15.95 mm diameter and produced the positive electrode with a film thickness of 30 micrometers.

<Production Example 2>
Production of negative electrode;
A slurry was obtained by sufficiently mixing 92.5 parts of graphite powder having an average particle size of about 8 to 12 μm, 7.5 parts of polyvinylidene fluoride and 200 parts of N-methylpyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.] in a mortar. The obtained slurry was applied to one side of a 20 μm thick copper foil, dried at 100 ° C. for 15 minutes to evaporate the solvent, punched to 16.15 mmφ, and made a negative electrode with a thickness of 30 μm using a press. did.

<Production Example 3>
Production of secondary battery cells;
A positive battery and a negative electrode obtained in Production Examples 1 and 2 were arranged at both ends in the 2032 type coin cell so that the respective coated surfaces faced to produce a secondary battery cell.

<Production Example 4>
Synthesis of methyl 2-butenoate-tri (3,6-dioxaheptyl) ammonium hexafluorophosphate (hereinafter abbreviated as A-1); [In the general formula (2), R ⁴ is an ethylene group, R ⁵ Is a methyl group, Q is an organic group in which R ⁶ is a methylene group, Q ¹ and Q ² are hydrogen atoms, Q ³ is a methoxycarbonyl group in the general formula (3), n is 2, and a is 1 and Y ⁻ is PF ₆ ^— ]
To a flask equipped with a stirrer, a thermometer and a condenser tube, 1.0 part (3.1 mmol) of tri (3,6-dioxaheptyl) amine [manufactured by Tokyo Chemical Industry Co., Ltd.], 4-bromo-2- 0.55 parts (3.1 mmol) of butenoic acid methyl ester [Tokyo Chemical Industry Co., Ltd.] and 10 parts of acetonitrile were charged and dissolved uniformly with stirring, and then reacted at room temperature for 24 hours with stirring. LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.47 part (3.1 mmol) was added to the reaction mixture, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified by an alumina column (150 mesh, Blockman1, standard grade, manufactured by Aldrich) using acetone as a solvent, and methyl 2-butenoate-tri (3,6-dioxaheptyl). 1.41 parts (2.5 mmol) of ammonium hexafluorophosphate (A-1) was obtained (yield 81%).

<Production Example 5>
Synthesis of methyl 2-butenoate-tri (2-methoxyethyl) ammonium hexafluorophosphate (hereinafter abbreviated as A-2); [In the general formula (2), R ⁴ is an ethylene group and R ⁵ is a methyl group; , Q is an organic group in which R ⁶ is a methylene group, Q ¹ and Q ² are hydrogen atoms, Q ³ is a methoxycarbonyl group in the general formula (3), n is 1, and a is 1. Y ⁻ is PF ₆ ^— ]
In a flask equipped with a stirrer, a thermometer and a condenser, 1.0 part (5.2 mmol) of tri (2-oxabutyl) amine [manufactured by Tokyo Chemical Industry Co., Ltd.], 4-bromo-2-butenoic acid methyl ester [Tokyo Chemical Industry Co., Ltd.] 0.94 parts (5.2 mmol) and 10 parts of acetonitrile were charged and dissolved uniformly with stirring, and then reacted at room temperature for 24 hours with stirring. LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.79 part (5.2 mmol) was added to the reaction mixture, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified with an alumina column (150 mesh, Blockman 1, standard grade, manufactured by Aldrich) using acetone as a solvent, and methyl 2-butenoate-tri (2-oxabutyl) ammonium hexafluorophos. 1.96 parts (4.5 mmol) of Fart (A-2) was obtained (yield 87%).

<Production Example 6>
Synthesis of di (2-butenoate methyl) -di (3,6,9-trioxadecyl) ammonium hexafluorophosphate (hereinafter abbreviated as A-3); [in the general formula (2), R ⁴ represents An ethylene group, R ⁵ is a methyl group, Q is an organic group in which R ⁶ is a methylene group, Q ¹ and Q ² are hydrogen atoms, Q ³ is a methoxycarbonyl group in the general formula (3), and n is 3. A compound in which a is 2 and Y ⁻ is PF ₆ ^— .
To a flask equipped with a stirrer, a thermometer and a condenser tube, 1.0 part (3.2 mmol) of di (3,6,9-trioxadecyl) amine [manufactured by Tokyo Chemical Industry Co., Ltd.], 4-bromo- 2-butenoic acid methyl ester [Tokyo Kasei Kogyo Co., Ltd.] 1.16 parts (6.4 mmol) and 10 parts of acetonitrile were charged and dissolved uniformly with stirring, and then reacted at room temperature for 24 hours with stirring. . To the reaction mixture, 0.49 part (3.2 mmol) of LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] was added, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified by an alumina column (150 mesh, Blockman 1, standard grade, manufactured by Aldrich) using acetone as a solvent, and di (2-butenoic acid methyl) -di (3, 6, 9 -Trioxadecyl) ammonium hexafluorophosphate (A-3) 1.35 parts (2.9 mmol) was obtained (yield 91%).

<Production Example 7>
Synthesis of (3,6,9,12,15-pentaoxahexadecyl) -tri (methyl 2-butenoate) ammonium hexafluorophosphate (hereinafter abbreviated as A-4); [in general formula (2) R ⁴ is an ethylene group, R ⁵ is a methyl group, Q is an organic group in which R ⁶ is a methylene group, Q ¹ and Q ² are hydrogen atoms, and Q ³ is a methoxycarbonyl group in the general formula (3), Compound in which n is 5, a is 3, and Y ⁻ is PF ₆ ^—
To a flask equipped with a stirrer, a thermometer and a condenser tube, 1.0 part (4.0 mmol) of 3,6,9,12,15-pentaoxahexadecylamine [manufactured by Tokyo Chemical Industry Co., Ltd.], 4- Bromo-2-butenoic acid methyl ester [manufactured by Tokyo Chemical Industry Co., Ltd.] 2.14 parts (12.0 mmol) and 10 parts of acetonitrile were charged and dissolved uniformly with stirring, and then reacted at room temperature with stirring for 24 hours. I let you. LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.60 part (4.0 mmol) was added to the reaction mixture, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified by an alumina column (150 mesh, Blockman 1, standard grade, manufactured by Aldrich) using acetone as a solvent, (3, 6, 9, 12, 15-pentaoxahexadecyl) -1.16 parts (3.5 mmol) of tri (methyl 2-butenoate) ammonium hexafluorophosphate (A-4) was obtained (yield 88%).

<Production Example 8>
Synthesis of 2-acryloyloxyethyl-tri (3,6-dioxaheptyl) ammonium hexafluorophosphate (hereinafter abbreviated as A-5); [in the general formula (2), R ⁴ is an ethylene group, R ⁵ Is a methyl group, Q is an acryloyloxyethyl group, n is 2, a is 1, and Y ⁻ is PF ₆ ^— .
To a flask equipped with a stirrer, a thermometer and a condenser, 1.0 part (3.1 mmol) of tri (3,6-dioxaheptyl) amine [manufactured by Tokyo Chemical Industry Co., Ltd.], 2-chloroethyl acrylate [ Tokyo Chemical Industry Co., Ltd.] 0.42 part (3.1 mmol) and 10 parts of acetonitrile were charged and dissolved uniformly with stirring, followed by reaction at room temperature for 24 hours with stirring. LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.47 part (3.1 mmol) was added to the reaction mixture, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified by an alumina column (150 mesh, Blockman1, standard grade, manufactured by Aldrich) using acetone as a solvent, and 3-acryloyloxyethyl-tri (3,6-dioxaheptyl) was purified. 1.47 parts (2.6 mmol) of ammonium hexafluorophosphate (A-5) was obtained (yield 84%).

<Production Example 9>
Synthesis of N- (methyl 2-butenoate) -N ′-(3,6-dioxaheptyl) imidazolium hexafluorophosphate (hereinafter abbreviated as A-6); [R ¹ in general formula (1) Is an organic group in which R ² is an ethylene group, R ³ is a methyl group, Q is a general formula (3), R ⁶ is a methylene group, Q ¹ and Q ² are hydrogen atoms, and Q ³ is a methoxycarbonyl group A compound wherein m is 2 and X ⁻ is PF ₆ ^—
To a flask equipped with a stirrer, a thermometer and a condenser, N- (3,6-dioxaheptyl) imidazole [manufactured by Tokyo Chemical Industry Co., Ltd.] 1.0 part (5.9 mmol), 4-bromo-2 -Butenoic acid methyl ester [manufactured by Tokyo Chemical Industry Co., Ltd.] 1.05 part (5.9 mmol) and 10 parts of acetonitrile were charged and dissolved uniformly with stirring, and then reacted at room temperature for 24 hours with stirring. LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.89 part (5.9 mmol) was added to the reaction mixture, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified by an alumina column (150 mesh, Blockman 1, standard grade, manufactured by Aldrich) using acetone as a solvent, and N- (methyl 2-butenoate) -N ′-(3, 6.99 parts (4.8 mmol) of 6-dioxaheptyl) imidazolium hexafluorophosphate (A-6) was obtained (yield 81%).

<Production Example 10>
Synthesis of N- (methyl 2-butenoate) -N ′-(3,6-dioxaheptyl) -2-methylimidazolium hexafluorophosphate (hereinafter abbreviated as A-7); ) In which R ¹ is a methyl group, R ² is an ethylene group, R ³ is a methyl group, Q is a general formula (3), R ⁶ is a methylene group, Q ¹ and Q ² are hydrogen atoms, and Q ³ is a methoxycarbonyl group A compound in which m is 2 and X ⁻ is PF ₆ ^—
To a flask equipped with a stirrer, a thermometer and a condenser, N- (3,6-dioxaheptyl) -2-methylimidazole [manufactured by Tokyo Chemical Industry Co., Ltd.] 1.0 part (5.4 mmol), 4 -Bromo-2-butenoic acid methyl ester [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.97 part (5.4 mmol) and 10 parts of acetonitrile were uniformly dissolved with stirring, and then stirred at room temperature for 24 hours. Reacted. LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.82 part (5.4 mmol) was added to the reaction mixture, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified by an alumina column (150 mesh, Blockman 1, standard grade, manufactured by Aldrich) using acetone as a solvent, and N- (methyl 2-butenoate) -N ′-(3, 6-Dioxaheptyl) -2-methylimidazolium hexafluorophosphate (A-7) (2.04 parts, 4.8 mmol) was obtained (yield 89%).

<Production Example 11>
Synthesis of N- (methyl 2-butenoate) -N ′-(3,6-dioxaheptyl) -2-ethylimidazolium hexafluorophosphate (hereinafter abbreviated as A-8); ) In which R ¹ is an ethyl group, R ² is an ethylene group, R ³ is a methyl group, Q is a general formula (3), R ⁶ is a methylene group, Q ¹ and Q ² are hydrogen atoms, and Q ³ is a methoxycarbonyl group A compound in which m is 2 and X ⁻ is PF ₆ ^—
In a flask equipped with a stirrer, a thermometer and a condenser, N- (3,6-dioxaheptyl) -2-ethylimidazole [manufactured by Tokyo Chemical Industry Co., Ltd.] 1.0 part (5.0 mmol), 4 -Bromo-2-butenoic acid methyl ester [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.90 parts (5.0 mmol) and 10 parts of acetonitrile were uniformly dissolved with stirring, and then stirred at room temperature for 24 hours. Reacted. LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.77 part (5.0 mmol) was added to the reaction mixture, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified by an alumina column (150 mesh, Blockman 1, standard grade, manufactured by Aldrich) using acetone as a solvent, and N- (methyl 2-butenoate) -N ′-(3, 6.79 parts (4.0 mmol) of 6-dioxaheptyl) -2-ethylimidazolium hexafluorophosphate (A-8) were obtained (yield 80%).

<Production Example 12>
Synthesis of N- (methyl 2-butenoate) -N ′-(3,6-dioxaheptyl) -2-ethylimidazolinium hexafluorophosphate (hereinafter abbreviated as A-9); [(A-8 ) Is a compound in which the imidazolium skeleton is imidazolinium]
To a flask equipped with a stirrer, thermometer and condenser, N- (3,6-dioxaheptyl) -2-ethylimidazoline [manufactured by Tokyo Chemical Industry Co., Ltd.] 1.0 part (5.0 mmol), 4 -Bromo-2-butenoic acid methyl ester [manufactured by Aldrich] 0.90 part (5.0 mmol) and 10 parts of acetonitrile were charged and dissolved uniformly with stirring, and then reacted at room temperature for 24 hours with stirring. LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.77 part (5.0 mmol) was added to the reaction mixture, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified by an alumina column (150 mesh, Blockman 1, standard grade, manufactured by Aldrich) using acetone as a solvent, and N- (methyl 2-butenoate) -N ′-(3, 6.69 parts (3.8 mmol) of 6-dioxaheptyl) -2-ethylimidazolinium hexafluorophosphate (A-9) was obtained (yield 76%).

<Production Example 13>
Synthesis of 4-vinylbenzyl-tri (3,6-dioxaheptyl) ammonium hexafluorophosphate (hereinafter abbreviated as A-10); [in the general formula (2), R ⁴ is an ethylene group, and R ⁵ is A methyl group, Q is an organic group in which R ⁷ is a methylene group, Q ⁴ , Q ⁵ , Q ⁶ and Q ⁷ are hydrogen atoms in the general formula (4), n is 2, and a is 1 Wherein Y ⁻ is PF ₆ ^— .
In a flask equipped with a stirrer, a thermometer and a condenser, 1.0 part (3.1 mmol) of tri (3,6-dioxaheptyl) amine [manufactured by Tokyo Chemical Industry Co., Ltd.], 4-chloromethylstyrene [ Tokyo Chemical Industry Co., Ltd.] 0.47 parts (3.1 mmol) and 10 parts of acetonitrile were charged and dissolved uniformly with stirring, followed by reaction at room temperature for 24 hours with stirring. LiPF ₆ [manufactured by Tokyo Chemical Industry Co., Ltd.] 0.47 part (3.1 mmol) was added to the reaction mixture, and the mixture was further reacted for 24 hours. Acetonitrile was removed by reduced pressure (10 mmHg), and then purified by an alumina column (150 mesh, Blockman1, standard grade, manufactured by Aldrich) using acetone as a solvent, and methyl 2-butenoate-tri (3,6-dioxaheptyl). 1.48 parts (2.5 mmol) of ammonium hexafluorophosphate (A-10) was obtained (yield 81%).

<Examples 1 to 23>
Adjustment of electrolyte additives;
Each raw material of the additive for electrolyte solution described in Table 1 and Table 2 was mix | blended, and the additive for electrolyte solution (Examples 1-23) was produced. In addition, the following were used for each raw material described in Table 1 and Table 2.
(B-1): Dimethoxyethane (number of donors = 24)
(B-2): Diethylene glycol diethyl ether (donor number = 22)
(B-3): Triethylene glycol diethyl ether (donor number = 25)
(B-4): Decaethylene glycol dipentyl ether (number of donors = 25)
(B-5): Dimethyl sulfoxide (number of donors = 30)
(B-6): Dibutyl sulfoxide (donor number = 27)
(C-1): Vinylene carbonate (C-2): Di-n-propyl vinylene carbonate (C-3): Vinyl ethylene carbonate (C-4): Divinyl carbonate (D-1): 1,4-butanediol di Vinyl ether (D-2): Diethylene glycol divinyl ether (D-3): 1,4-bis (vinyloxymethyl) cyclohexane

<Examples 24-45>
Adjustment of the electrolyte;
Ethylene carbonate: diethyl carbonate = 1: 1 (weight ratio) mixed solvent, the LiPF ₆ was dissolved to a concentration of 1 mol / L as an electrolyte, to prepare a electrolyte solution. To the obtained electrolyte solution, (X-1) to (X-23) obtained in Examples 1 to 23 are added so as to have the addition amounts shown in Table 3 and Table 4, respectively, until uniform transparency is obtained. Stirring and adjusting the electrolyte solutions of Examples 24-45.

<Comparative Example 1>
The electrolyte solution of Comparative Example 1 was obtained using the electrolyte solution as it was (without adding an additive for electrolyte solution).

<Comparative example 2>
To 97 parts of the electrolyte solution, 3 parts of vinylene carbonate (VC) was added and stirred until uniform and transparent to prepare the electrolyte solution of Comparative Example 2.

  The electrolyte solutions prepared in Examples 24-45 and Comparative Examples 1 and 2 were each injected into a secondary battery cell and sealed, and the battery output and charge / discharge cycle characteristics were measured by the following methods. The results are shown in Tables 3 and 4.

<Evaluation of battery output>
Using a charge / discharge measurement device “Battery Analyzer 1470” [manufactured by Toyo Technica Co., Ltd.], charge so that SOC (State of charge, the ratio of the capacity in a fully charged state to the capacity at a predetermined time) is 60%. Then, discharge at a constant current and read the voltage after 10 seconds. This operation is performed with several current values, and the current value on the horizontal axis and the voltage value after 10 seconds are plotted on the vertical axis to create an approximate line, and the current value (I ₃ when the approximate line intersects with 3V) _.0V ) and battery output is calculated from the following formula.
Battery output (W) = I _3.0V x 3.0
<Evaluation of charge / discharge cycle characteristics>
Using a charge / discharge measuring device “Battery Analyzer 1470 type” [manufactured by Toyo Technica Co., Ltd.], the battery was charged from 0 V to 2 V with a current of 0.2 mA / cm ² , and after resting for 10 minutes, 0.2 mA / cm ^The battery voltage was discharged to 0 V with a current of ² , and this charge / discharge was repeated. At this time, the battery capacity at the first charge and the battery capacity at the 50th cycle charge are measured, and the charge / discharge cycle characteristics are calculated from the following equation. It shows that charging / discharging cycling characteristics are so favorable that a numerical value is large.
Charging / discharging cycle characteristics (%) = (battery capacity at the 50th cycle charge / battery capacity at the first charge) × 100

  The lithium secondary battery produced using the additive for electrolytic solution of the present invention has high battery output and excellent charge / discharge cycle characteristics. The cause of the high output is considered to be that a polyethylene glycol film having high lithium ion conductivity is formed on the negative electrode surface, and the desolvation of lithium ions is accelerated. The reason why the charge / discharge cycle characteristics are improved is that the adhesion between the negative electrode protective film formed and the negative electrode surface is due to electrostatic interaction between the quaternary ammonium ion skeleton in the nitrogen-containing onium salt and the negative electrode surface. I think it is because it is getting higher.

When the additive for electrolytic solution of the present invention is added to a lithium secondary battery, the battery output and charge / discharge cycle characteristics are improved. Therefore, as an additive for electrolytic solution of a secondary battery for a mobile phone, a personal computer, a hybrid vehicle, etc. Useful. It can also be applied to a positive electrode protective film and an electrode protective film of a lithium ion capacitor.

Claims (14)

  At least one nitrogen atom in the nitrogen-containing onium salt is bonded to the organic group (a) having a polymerizable unsaturated bond, and the nitrogen atom or another nitrogen atom is bonded to the (poly) oxyalkylene chain (b). The additive for electrolyte solutions containing the nitrogen-containing onium salt (A) which has a structure.   The electrolyte solution additive according to claim 1, further comprising an electrolyte dissociation accelerator (B).   Furthermore, the additive for electrolyte solutions containing the carbonate compound (C) which has a polymerizable unsaturated bond.   Furthermore, the additive for electrolyte solutions containing the compound (D) which has a vinyl ether group or a propenyl ether group.   The additive for electrolytic solution according to any one of claims 1 to 4, wherein the nitrogen-containing onium salt (A) is an imidazolium salt and / or a quaternary ammonium salt. The additive for electrolytic solution according to claim 5, wherein the imidazolium salt is a salt represented by the general formula (1).
Wherein R ¹ is a hydrogen atom, a methyl group or an ethyl group; R ² is an alkylene group having 2 to 4 carbon atoms; R ³ is an alkyl group having 1 to ³ carbon atoms; Q is an organic compound having a polymerizable unsaturated bond. group (a); m is the number of 1 to 10; X ^- represents an anion). The additive for an electrolytic solution according to claim 5, wherein the quaternary ammonium salt is a salt represented by the general formula (2).
(Wherein R ⁴ is an alkylene group having 2 to ⁴ carbon atoms; R ⁵ is an alkyl group having 1 to 3 carbon atoms; Q is an organic group (a) having a polymerizable unsaturated bond; n is a number from 1 to 5) ; a is an integer from 1 to 3; Y ^- represents an anion). The electrolytic solution according to claim 1, wherein the organic group (a) is a group represented by the general formula (3), a group represented by the general formula (4), or a (meth) acryloyloxyalkyl group. Additives.
(In the formula, R ⁶ is an alkylene group having 1 to 3 carbon atoms, and Q ¹ , Q ² and Q ³ are each independently a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a phenyl group, a halogen atom. , A fluoroalkyl group, a cyano group, a carboxyl group, an alkoxy group, and an alkoxycarbonyl group.
(In the formula, R ⁷ is an alkylene group having 1 to 3 carbon atoms, Q ⁴ is a hydrogen atom or a halogen atom, and Q ⁵ , Q ⁶ and Q ⁷ are each independently a hydrogen atom and a carbon number of 1; -4 alkyl group, phenyl group, halogen atom, fluoroalkyl group, cyano group, carboxyl group, alkoxy group and alkoxycarbonyl group.   The electrolyte solution additive according to any one of claims 2 to 8, wherein the electrolyte dissociation accelerator (B) is a sulfoxide compound having a donor number of 16 to 40 and / or an ether compound having a donor number of 16 to 40. The additive for an electrolytic solution according to claim 9, wherein the sulfoxide compound is a sulfoxide compound represented by the general formula (5).
(In the formula, R ⁸ and R ⁹ are each independently an alkyl group having 1 to 5 carbon atoms.) The additive for electrolytic solution according to claim 9, wherein the ether compound is an ether compound represented by the general formula (6).
R ¹⁰ —O— (CH ₂ CH ₂ O) _n —R ¹¹ (6)
(Wherein R ¹⁰ and R ¹¹ are each independently an alkyl group having 1 to 5 carbon atoms; n is a number of 1 to 10) The additive for an electrolytic solution according to any one of claims 3 to 11, wherein the carbonate compound (C) is a compound represented by the general formula (7) and / or a compound represented by the general formula (8).
(In the formula, R ¹² and R ¹³ are each independently a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.)
(In the formula, R ¹⁴ and R ¹⁵ are each independently a hydrogen atom or an alkenyl group having 2 to 3 carbon atoms, and R ¹⁴ and R ¹⁵ are not both hydrogen atoms.) The compound (D) is a cyclohexane derivative having one or more vinyl ether groups or propenyl ether groups, a compound represented by the general formula (9), or a compound represented by the general formula (10). The additive for electrolyte solutions as described above.
R ¹⁶ —CH═CH—O— (CH ₂ ) _p —O—CH═CH—R ¹⁷ (9)
(In the formula, R ¹⁶ and R ¹⁷ are each independently a hydrogen atom or a methyl group, and p is a number of 4 to 10.)
R ¹⁸ —CH═CH—O— (C ₂ H ₄ O) _q —O—CH═CH—R ¹⁹ (10)
(In the formula, R ¹⁸ and R ¹⁹ are each independently a hydrogen atom or a methyl group, and q is a number of 1 to 5.) An electrolytic solution comprising a nonaqueous solvent, an electrolyte, and the additive for electrolytic solution according to claim 1.